Generally, in a manufacturing process of a semiconductor device, various kinds of processes such as, for example, dry etching, sputtering, and CVD (Chemical Vapor Deposition) are repeatedly applied to a semiconductor wafer. Many of the above various processes are performed under a vacuum atmosphere, and load openings through which the wafer is loaded/unloaded into/from process chambers for these kinds of processes are sealed by gate valve apparatuses in a highly airtight state during the processes.
A gate valve apparatus of this type is, for example, mounted on a load opening which is formed on a sidewall of an evacuatable process chamber and has a narrow width large enough to allow the passage of the wafer. During the process, the process is performed in a state where the load opening is airtightly closed by a valve element, which is provided with an O-ring or the like, of the gate valve apparatus.
Here, as shown in FIG. 15 and FIG. 16, a conventional gate valve apparatus 100 has a casing 102, a valve element 104 drivably provided in the casing 102, and a valve element driving unit 106 which rotary drives the valve element 104 and thereafter presses the valve element 104 toward a valve seat. Further, in the casing 102, formed are a first opening 108 through which the casing 102 communicates with an adjacent process chamber (not shown) and a second opening 110 through which the maintenance of a later-described sealing member 112 provided in the valve element 104 is performed. The valve element 104 is capable of closing the first opening 108 or the second opening 110 when rotary driven and pressed toward the valve seat by the valve element driving unit 106. On a front surface of the valve element 104, there are provided the sealing member 112 for airtightly sealing the first opening 108 when the valve element 104 closes the first opening 108 and a sealing member 114 for airtightly sealing the second opening 110 when the valve element 104 closes the second opening 110.
The above-described structure has a problem, as shown in FIG. 17, that portions, of the valve element 104, close to its longitudinal both ends come into contact with sidewalls of the casing 102 (see a portion S shown in FIG. 17) when the valve element 104 closes the first opening 108 after the valve element 104 closes the second opening 110 during the maintenance of the sealing member 112 and then the maintenance is finished, which necessitates increasing the size of the casing or greatly moving the valve element 104 in a direction of the center of rotation before rotary driving the valve element 104. Greatly moving the valve element 104 in the direction of the center of rotation results in a decrease in a rotary drive radius r of the valve element 104, which can solve the problem of the contact (interference) of part of the valve element 104 with the sidewall of the casing 102.
Patent document 1: Japanese Patent Application Laid-open No. Hei 8-60374